Nonstop action, romance, and also the mystery of the whole book is what makes this book a good young adult thriller. And really, it is a pretty good combination.For some reason, while I was reading this book, I kept comparing this book to Sound of Thunder. I have no idea why, but I just found myself doing it. I guess why is that it held some similarities. Like, in this book they wake up and the land outside is barren and there are mysterious animal footprints. In Sound of Thunder, after they time travel back, the land is ravaged, and there are meat-eating animals. That is mainly the only similar thing that I really found, but I enjoyed comparing the two of them.( If you aren't familiar with Sound of Thunder, you should look it up!)The constant mysterious air in Strangelets is what had me in suspense and and anticipation during the whole book. I had so many questions flying through my head. Why did they end up in this hospital? How did they all end there? What had happened to all the people? Those are just a few examples of my thoughts while reading it. Gagnon really did a well job creating all the action and mystery contained in the plot in the book. It kept me sitting on edge throughout it!While I mostly enjoyed the action and mystery in this book, I did have some problems with the romance. Again, I have to mention that I HATE pretty much all insta-love in books. They usually don't hold much meaning in them and end up cheesy as heck. This book definitely had some insta-love. This book takes place in maybe, 3 or 4 days, and you can only assume that, of course, it is insta-love. I guess, in order to have romance in this book, it would only end up being insta-love. It never extremely bothered me, but it did make me a tiny bit disappointed.Overall, this book is something you want to look out for if you're into nonstop action, mystery, or are just looking for a thriller!